[gta02-core] Audio ECNs, a bit of progress
rehar at saweb.de
Thu Aug 20 20:07:35 CEST 2009
Werner Almesberger wrote:
> Some news from the ECN front:
> - I finished ECN0031, which describes how to use the codec interrupt
> for HOLD and JACK_INSERT instead of involving the CPU directly.
> This is from Joerg's "Mega-ECN".
So far, looks good to me, I'll do a full review later today.
> - I updated ECN0015 (removal of the Calypso's rear entrance through
> the audio jack) with the changes that have actually been done.
> I wonder if we shouldn't get rid of R4405/7 completely instead of
> making them 0R. We'll have to add some EMI and ESD protection, so
> there will be room for interrupting the circuit, if necessary.
Thanks, I planed on removing them that's why I wrote this into the ECN.
Actually, I wanted to discuss this first but I probably forgot about it.
Any comments? Otherwise I'll remove them.
> Once the final fate of R4405/7 is decided, we can move ECN0015
> to "Done".
> - we have one regression: the ESD protectors D3001 and D3002 (at
> the front speaker) were lost in translation.
Right, they got lost. I'll add them.
> I still have more items to process from the "mega-ECN". Here's my
> "to do" list:
> - new ECN: add ESD to jack
Yes, it's probably a really good idea to add ESD protection to all pins
of the Jack as it is in Joerg's proposal.
> - buzz prevention: remove 22 pF caps around jack, place EMI filters
> (C4403, C4404, C4405), remove common-mode choke B4102
I'd definitely go for the Pi filter in all of the headphone lines and
> - bass fix: add component, remove R4405/7 (0R for us)
> - bass fix: big caps (~100 uF), tantalum, no cer
> - new suppression:
> we might consider making each of C3012/13 a 4u7 + 47p couple
> as that should rather completely short any RF induced to the "hot" side of
> those C (chip side) to GND
> - buzz fix: provide place for bigC
> - rear ECN: merge 18 pF + 47 pF into 56 pF
Do we have already 56pF in the BOM or does that mean we need a new
> - new ECN: swap rear choke / caps
> - new ECN: remove C3020
Sure, it's NC right now, so there shouldn't be a problem with removing
> - new ECN: increase input caps from 100 nF to 1 uF (ceramic)
> (1uF) according to wolfson appnotes
> - mic out caps
> - RXN/RXP (modem to codec)
> - MONO1/MONO2 (codec to modem)
> - new ECN: route LOUT1/ROUT2 back to LINE1/LINE2
This needs to be checked more in detail because we'd use polarized
tantalum caps for output coupling which can get damaged when operated
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